I'm pretty sure it was called `string_2` to remain generic enough for this type of thing. If not `string_2` then use `string_3` or `string_4` which I don't believe are used much.
Hum, so these names are not clear enough and should be better documented; because my understanding was rather that the `string_N` where for different kind of strings (plain, raw, here document, etc.), and I always mapped with this concept in mind.